Sheet feeding device

ABSTRACT

A device for feeding individual sheets of a stack to apparatus in which these sheets are to be processed further, which comprises a sheet transporting element having a plane underside of non-slippery material which may be brought into contact with the uppermost sheet of the stack, said sheet transporting element being provided with means for moving it backwards and forwards in the direction of transportation of the sheets.

United States Patent [:91

Marx et al.

[ Mar. 18, 1975 1 SHEET FEEDING DEVICE [75] Inventors: Gerhard Marx,Taunusstein; Gunter Kramer, Wiesbaden, both of Germany [73] Assignee:Kalle Aktiengesellschal't,

Wiesbaden-Biebrich, Germany [22] Filed: Jan. 16, 1973 [21] Appl. No.:324,234

[30] Foreign Application Priority Data Jan 17, 1972 Germany 2202024 [52]US. Cl 271/42, 221/210, 221/276, 271/167, 271/208 [51] Int. Cl B65h3/02, B65h 3/52 [58] Field of Search 271/42, 145, 167, 169, 271/208,104, 121, 137; 221/228, 244, 210,

[56] References Cited UNITED STATES PATENTS 747,344 12/1903 Allen 271/422,086,138 7/1937 Roque 271/42 2,883,190 4/1959 Manthey 317/2 R X3,269,590 8/1966 Harter 271/42 X 3,306,491 2/1967 Eisner et a1 .1271/117 3,421,753 1/1969 Staples 271/42 X 3,640,524 2/1972 Fredrickson271/42 X Primary ExaminerEvon C. Blunk Assistant Examiner-James W.Miller Attorney, Agent, or Firm-Stevens, Davis Miller & Mosher [57]ABSTRACT A device for feeding individual sheets of a stack to apparatusin which these sheets are to be processed further, which comprises asheet transporting element having a plane underside of non-slipperymaterial which may be brought into contact with the upper most sheet ofthe stack, said sheet transporting element being provided with means formoving it backwards and forwards in the direction of transportation ofthe sheets.

17 Claims, 3 Drawing Figures PATEIHEB HAR 1 8 m5 SHEET 2 BF 2 Fig.2

Fig.3

1 SHEET FEEDING DEVICE The present invention relates to a device forfeeding individual sheets of a stack to an apparatus in which the sheetsare processed further, for example a copying apparatus.

The feeding of individual sheets from a stack toa copying apparatusrepresents a problem which has hitherto not been satisfactorily solvedin the art. Numerous attempts have been made in this field. There arefeeding devices with circulating chains, devices with friction rollersand needle gripping devices. However, these devices are either extremelyinvolved in construction and therefore unusable for simple apparatus, ordo not operate with sufficient reliability. Feeding sheets from a stackproves particularly difficult where precoated sheets are concerned,especially electrophotographic recording material, for example zincoxide paper.

There is therefore a need for a sheet feeding apparatus which is simplein construction and cheap to manufacture and may also be used with smallmanual copying apparatures. The apparatus should have a high degree ofreliability that several sheets will not be fed simultaneously, andshould at the same time be rapidly and reliably utilisable.

The present invention accordingly provides a device for feedingindividual sheets of a stack to apparatus in which these sheets are tobe processed further, especially an electrophotographic copying machine,which comprises a sheet transporting element having a plane underside ofnon-slippery material, preferably nonslippery foam material, which maybe brought into contact with the uppermost sheet of the stack, saidsheet transporting element being provided with means, preferablycomprising at least one telescopic rod system for moving it backwardsand forwards in the direction of the transportation of the sheets.

The means for moving the sheet transporting element preferably comprisesat least one telescopic rod system running downwards at an angle andbackwards through the sheet transporting element, relative to the sheettransporting direction.

The present invention also provides a process for supplying individualsheets from a stack to apparatus in which the sheets are to be furtherprocessed, especially an electrophotographic copying machine, using thedevice of the invention. n displacing the telescopic rod system in thesheet transporting direction, the telescopic rod system is self'lockingto prevent telescoping, and hence the uppermost sheet is shiftedrelative to the stack, whilst during the return movement the telescopicrod system is slightly telescoped and, as a result of the inclinedposition, as in the case of a sloping plane, the non-slipperytransporting element is lifted off the uppermost sheet of the stack ofsheets and hence the paper is not buckled but remains lying flat. Thisdevice is of extremely simple construction and permits rapid andreliable feeding, especially of zinc oxide copying papers to anelectrophotographic reproduction apparatus.

The angle between the telescopic rod system and the normal to the papershould preferably be in the range of from 5 to an angle of about l3between the telescopic rod system and the normal to the paper (or of 77'between the telescopic rod system and the paper surface) has provedparticularly satisfactory.

The transporting element can be arranged particularly simply to bedisplaceable in the device by providing, in the lid above the stack, aslit in which a slider is displaceably mounted, the end of thetelescopic rod system being fixed thereto. The slope of the telescopicrod system is of decisive importance and is always kept constant whilstthe complete stack is being fed, since the telescopic rod system is notarranged so that it can be tilted. As the stack becomes smaller, thetransporting element nevertheless remains in engagement with the sheetof the copying stack which is uppermost at any time, since thetelescopic rod system is automatically extended as the stack heightdecreases.

The device of the invention preferably comprises a box to hold the stackof sheets, wherein the front transverse wall, that is the walltransverse to the sheet transporting direction towards which the sheetsare to be transported, slopes outwards from the bottom of the box. Thefront transverse wall thus acts as a ramp for the sheets to betransported. Preferably the rear transverse wall is also sloped andparallel to the front transverse wall. The two sloping transversedefining walls also always cause a little fanning of the papers oninsertion into the sheet stacking device. This permits air to penetratebetween the individual sheets and thereby enables them to be drawn offmore readily.

Further reliability in ensuring that several sheets are not fedsimultaneously is achieved if the front sloping transverse wallpossesses at least one strip, having a rough surface, running in thesheet transporting direction. The front edge of the sheet flicks alongthis strip and a further sheet which may have been fed with it isretained by the roughness. Here, it is particularly advantageous if therough strip on the front transverse defining wall is somewhat broader atthe bottom than at the top, that is to say if it tapers conically. Thispermits very reliable feeding of single sheets particularly also for thebottom sheets of a stack of sheets. The strip having a rough surface canbe formed particularly simply by a glued-on fabric strip of notexcessively rough structure.

For electrophotographic apparatuses in which photoconducting sheetmaterial is to be fed to the apparatus it has proved particularlyadvantageous if the sheet stack is located in an insulated housing andthe outlet edge of this housing, that is to say, for example, the upperedge of the front sloping transverse defining wall, is electricallyconducting and exposed so that it comes into contact with the fed sheetand thus prevents the charge emanating from the corona from beingconducted into the stack of sheets.

The process is further facilitated if a return spring is provided in thedevice, between the housing and the transporting element displaceabletherein, this spring being tensioned when transporting the sheet andbeing capable of retracting the transporting element thereafter to itsstarting position. At the same time it is preferred to locate amicro-switch in the device in such a way that on displacing thetransporting element from the starting position the switching of themicro-switch causes the various subsequent stations of an apparatus inwhich further processing of the sheets is to occur, for example anelectrophotographic apparatus, to be switched on.

The transporting element may suitably comprise a foam block to the topof which is fixed a metal plate, the telescopic rod system being fixedat an angle on to this metal plate. This construction is particularlyspacesaving if the outer sheath of the telescopic rod system is locatedin an appropriately shaped sloping bore of the foam block, the metalplate is bored and is connected to the extending end of the sheath. Theinner rod of the telescopic rod system can then be drawn out but therequisite height of the construction is kept low due to the fact thatthe length of the telescoped telescopic rod system and the thickness ofthe foam block are not additive.

The invention is described in further detail, by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 represents an enlarged vertical section along the line ll of FIG.2,

FIG. 2 represents a plan view of a device according to the invention,with the lid 12 omitted, and

FIG. 3 represents a detail of the device shown in FIG. 1, taken alongthe line III-11] of FIG. I.

An angled metal sheet 2 is located in a housing 1. This sheet 2 has abottom section 2a and two sloping sections 2b and 2c which are parallelto one another. The two sloping sections 2b and 2c of the sheet 2represent the sloping transverse defining walls for a stack of sheets 17consisting of sheets of zinc oxide paper. Furthermore, a removable coverplate 12 and a guide sheet 3 are provided. The guide sheet 3 causes thepaper sheet which has been pushed forward to be moved in the directionof guiding elements which are not shown, for example transporting beltsof an electrophctographic copying apparatus.

Laterally, the stack of sheets 17 is held by two guide sheets 4 and 5which are internally lined with felt-like or velvet-like fabric 413 and5B. At the same time, one guide sheet 5 is lightly pressed against thestack 17 by means of a spring 13 or a foam slab.

A foam block 6 of soft porous foam rests on the uppermost sheet of thestack of sheets 17. A block of "Moltopren (Trade Mark, product ofBeiersdorf A.G., Hamburg, Germany) or similar material has proved verysuccessful. A metal plate 18 is fixed to this block. Furthermore, theblock 6 possesses a sloping bore in which is located the outer sheathofa telescopic rod system 7. This sheath is soldered to the plate 18 inthe desired sloping position, as is indicated schematically by thesoldering point 19.

The extensible rod of the telescopic rod system 7 is connected at itsend to an angled metal sheet 8, which in turn is connected to a handle10. The handle with the metal sheet 8 located below it and thetelescopic rod system fixed thereto, as well as the Moltopren block 6,can be pushed to and fro in a slit in the lid 12. The paper transportingdirection is here indicated by the arrow 20. On moving the unit 6, 7, 8,10 in the direction of the arrow 20, a normal force N, is producedbetween the two components of the telescopic rod system 7, which acts atright angles to the direction in which the telescopic rod is guided. Ascan be seen from the left-hand triangle of forces shown in FIG. 1, thisnormal force N. is substantially directed towards the lower left-handcorner. It may be split into a downwardly directed vertical force Vcorresponding to the weight of the foam block 6 and that of the plate18, and a horizontal frictional force R The vertical component V,effects the necessary pressure of the foam block 6 and thus causes theuppermost sheet to be pushed forward. If the handle 10 and the unit 6,7, 8

connected thereto are then moved to the right, a normal force N, isproduced which is directed toward the right top corner, as shown in theright-hand triangle of forces. This normal force is composed of africtional force R, and a vertical force V Due to this verticalcomponent V the foam block has a tendency to climb along the telescopicrod 7, and the top sheet of the stack of sheets is thus relieved. Thisrelief is only effective as long as there is at least a slight contact(friction) between the foam block 6 and the uppermost sheet of thestack. It is also possible, and comes within the scope of the presentinvention, for the foam block 6 to be in lateral contact with thefelt-or velvet-covered guides 48 and 5B, in which case it could becompletely lifted from the stack of sheets. The first-mentionedembodiment is preferred, however, since it is not necessarily desirablethat the foam block 6 is completely lifted, because a residual friction,which may even cause a slight displacement of the following sheet,facilitates the separation of the next sheet from the stack.

A return spring 14 is mounted between the edge of the lid l2 and theangled metal sheet 8. When the handle 10 is moved in the direction ofthe arrow 20, this spring is tensioned and automatically pulls the foamblock 6 back to its starting position when the top sheet has been pushedforward.

A micro switch ll is located in the device in such a way that themovement of the handle 10 switches on, for example, the corona dischargedevice and the further transport devices of an electrophotographicapparatus.

Particularly good and reliable separation into individual sheets isachieved by the measure described below. Two narrow fabric strips 15 areglued onto the base 2a and the front sloping transverse defining wall2b. These fabric strips, consisting of a fabric which is not excessivelycoarse (the self-adhesive *Leukoplast" tape manufactured for medicalpurposes by Messrs. Beiersdorf A.G., Hamburg, has proved successful)terminate just before the upper edge 3A of the sloping transversedefining wall 212. Furthermore, the base sheet of metal 2 iselectrically insulated from the paper stack by means of thin insulatingstrips 16 (about 20 a thick). On displacing a double sheet by means ofthe block 6 against the ramp" 2b, the edges of the sheet jump over theunevennesses of the fabric surface of the strips 15. As a result, thedouble sheets are separated from one another especially in theparticularly strongly adhering initial region. Air enters between sheetsand the inadvertent simultaneous transporting of two or more sheets isreliably prevented.

The exposed electrically conducting edge 3A, past which the zinc oxidepaper is pushed, prevents charge from flowing back from the immediatelyfollowing corona discharge device via the transported sheet into thestack of paper.

In the embodiment shown, a stack of paper of size DIN A4 wastransversely used. Four telescopic rod systems 7 were provided on theangled metal sheet 8. The extension length of the telescopic rod systems7 depends on the number of sheets which are supposed to be in the stack.The process was successfully carried out with a stack of 250 sheets. Itwas found, surprisingly, that no traces of the sheet feed mechanism wereto be found on the otherwise very sensitive zinc oxide paper. Afterhaving been used to transport several thousand sheets, no wear effectwas as yet detectable on the Moltopren block 6.

As a result of the sloping arrangement of the transverse defining walls2b and 2c, the stack of paper to be inserted in this lower section mustbe fanned. Hence air enters between the individual sheets. Furthermore,the adhesion of the cut edges, which results on cutting the sheets tosize, is broken. in this way, pushing off the sheets one by one isfacilitated.

Using the device described it was possible substantially to increase theoutput of an electrophotographic copying apparatus working with ZnOpaper. The possibility is provided, for the first time, to work, in acheap manual apparatus, not with pre-exposed papers but with paperswhich can be fed in from the dark. This substantially improves the copyquality and the working speed.

What is claimed is:

1. An apparatus for feeding individual sheets of a stack to a device onwhich said sheets are further worked comprising a reciprocating conveyorelement for the displacement of the top sheet of the stack and areciprocating telescopic rod comprising a rod and sheath. said conveyorelement having a flat bottom of gripping foam which contacts the topsheet of the stack, said telescopic rod being arranged to extendobliquely downwardly and rearwardly with respect to the sheet-co nveyingdirection and having its sheath fastened to the conveyor element.

2. A device as claimed in claim 1, wherein the angle between thetelescopic rod system and the normal to the paper is between 5 and 3. Adevice as claimed in claim 2, wherein the angle is about 13.

4. A device as claimed in claim 1, including a lid positioned above thestack, and provided with a slit in which a slider is displaceablymounted in the slit, one end of the telescopic rod being angularlyattached to the sider.

5. The device as claimed in claim 1, including a box having a front walltransverse to the sheet transporting direction, facing towards thedirection to which the sheets are to be transported and slopingoutwardly from the bottom of the box.

6. The device as claimed in claim 5, wherein said box has a rear walltransverse to the sheet transporting direction a portion of which isparallelly sloped to the front transverse wall.

7. The device as claimed in claim 5, wherein the front transverse wallis provided with at least one strip having a rough surface, running inthe sheet transporting direction.

8. The device as claimed in claim 7, wherein the strip of rough materialon the front sloping transverse wall tapers such that it is broader atthe bottom than at the top.

9. The device as claimed in claim 7, wherein the strip comprises a gluedon fabric strip.

10. The device as claimed in claim 1, including an insulated housingdefining an outlet edge for said sheets which is electrically conductingand so disposed that each sheet comes in contact therewith as it leavesthe housing.

11. The device as claimed in claim 10, wherein the electricallyconducting outlet edge comprises the upper edge of the sloping fronttransverse wall.

12. The device as claimed in claim 4, including a spring interconnectingthe slider and housing such that said spring is tensioned whentransporting a sheet and then retracts the transporting element to itsstarting position.

13. The device as claimed in claim 1, including a microswitch which canbe operated by the displacement of the sheet transporting element, saidrnicroswitch being connectable to apparatus in which further pro cessingof the sheets is to occur such as to actuate this further processingapparatus when the displacement of the sheet transporting elementoccurs.

14. The device as claimed in claim 13, wherein the apparatus in whichfurther processing is to occur comp ises an electrophotographicapparatus.

15. The device as claimed in claim 1, wherein the sheet transportingelement comprises a foam block to the top of which is fixed a metalplate, the telescopic rod being fixed at an angle onto this metal plate,and the metal plate being bored and connected to the extending end ofthe sheath of the telescopic rod.

16. The device as claimed in claim 15, wherein the outer sheath of thetelescopic rod is located in an approximately shaped bore of the foamblock.

17. The device as claimed in claim 1 for transporting sheets comprisingfour telescopic rods arranged transversely to the sheet transportingdirection and equidistant from one another.

* k i i

1. An apparatus for feeding individual sheets of a stack to a device onwhich said sheets are further worked comprising a reciprocating conveyorelement for the displacement of the top sheet of the stack and areciprocating telescopic rod comprising a rod and sheath, said conveyorelement having a flat bottom of gripping foam which contacts the topsheet of the stack, said telescopic rod being arranged to extendobliquely downwardly and rearwardly with respect to the sheet-conveyingdirection and having its sheath fastened to the conveyor element.
 2. Adevice as claimed in claim 1, wherein the angle between the telescopicrod system and the normal to the paper is between 5* and 20*.
 3. Adevice as claimed in claim 2, wherein the angle is about 13*.
 4. Adevice as claimed in claim 1, including a lid positioned above thestack, and provided with a slit in which a slider is displaceablymounted in the slit, one end of the telescopic rod being angularlyattached to the sider.
 5. The device as claimed in claim 1, including abox having a front wall transverse to the sheet transporting direction,facing towards the direction to which the sheets are to be transportedand sloping outwardly from the bottom of the box.
 6. The device asclaimed in claim 5, wherein said box has a rear wall transverse to thesheet transporting direction a portion of which is parallelly sloped tothe front transverse wall.
 7. The device as claimed in claim 5, whereinthe front transverse wall is provided with at least one strip having arough surface, running in the sheet transporting direction.
 8. Thedevice as claimed in claim 7, wherein the strip of rough material on thefront sloping transverse wall tapers such that it is broader at thebottom than at the top.
 9. The device as claimed in claim 7, wherein thestrip comprises a glued-on fabric strip.
 10. The device as claimed inclaim 1, including an insulated housing defining an outlet edge for saidsheets which is electrically conducting and so disposed that each sheetcomes in contact therewith as it leaves the housing.
 11. The device asclaimed in claim 10, wherein the electrically conducting outlet edgecomprises the upper edge of the sloping front transverse wall.
 12. Thedevice as claimed in claim 4, including a spring interconnecting theslider and housing such that said spring is tensioned when transportinga sheet and then retracts the transporting element to its startingposition.
 13. The device as claimed in claim 1, including a microswitchwhich can be operated by the displacement of the sheet transportingelement, said microswitch being connectable to apparatus in whichfurther processing of the sheets is to occur such as to actuate thisfurther processing apparatus when the displacement of the sheettransporting element occurs.
 14. The device as claimed in claim 13,wherein the apparatus in which further processing is to occur comprisesan electrophotographic apparatus.
 15. The device as claimed in claim 1,wherein the sheet transporting element comprises a foam block to the topof which is fixed a metal plate, the telescopic rod being fixed at anangle onto this metal plate, and the metal plate being bored andconnected to the extending end of the sheath of the telescopic rod. 16.The device as claimed in claim 15, wherein the outer sheath of thetelescopic rod is located in an approximately shaped bore of the foamblock.
 17. The device as claimed in claim 1 for transporting sheetscomprising four telescopic rods arranged transversely to the sheettransporting direction and equidistant from one another.